My hair's that long too. What's your regime? I think the problem is that you have more hair. I didn't have tangles when I had a twa cos there wasn't enough hair to get mixed up together.
Are you finger combing it dry? Cos there's no hope in help of detangling dry 4a/b hair and having some left. My suggestion is to get a good brush (I just moved on to a denman d3 from the d14) and a wide tooth comb and whilst your hair is FULL of conditioner run one of these through, don't try before or after the condtioner, that just makes the hair angry. I find that even when there's 3 million knots in dry hair, the water and conditioner help straighten them out even before I use the comb or brush
I used to COrinse/rinse everyday but it's cold here now - I'm guessin you don't have this problem - so now I only wash it on the weekends and daily I just remoisturise with some elasta qp recovery. After I wash it I put in in twists like my siggy and then all week wear the twistout, which of course shrinks by the day. BUT I don't try to detangle it every morning, I just rub the moisturiser into it and kinda fluff/rub it which makes it easier to manage.
I don't know how long you've been natural or how you got there (BC, trans etc) but I've heard other [long haired] naturals say that detangling is really an issue for straighter hair. As long as the tangles and knots aren't getting in the way of anything it's better to just leave them til wash day.
Anyway, update us on the situation, let us know how it's goin HHG